Browsing by Author "Al-Hagri, Mohammed Gamal"

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Citation - Scopus: 9
Effect and Optimization of Incorporation of Nano-Sio2 Into Cement-Based Materials – a Review
(2022) Al-Hagri, Mohammed Gamal; Döndüren, Mahmud Sami
Incorporation of nanomaterials into cement-based materials has great potentials to improve their performance to great levels and to produce construction materials with superior and unique properties. Various nanoparticles have been utilized in cementitious composites to improve their properties. This paper provides a detailed review about the effect of the most widely incorporated nanomaterial into cement-based materials, namely nano-silica, on different on properties of cement-based materials. The investigated properties are mechanical properties (compressive strength, split tensile strength and flexural strength), durability parameters (permeability, freeze and thaw resistance, high temperature resistance, fire resistance and sulfate attack resistance) and microstructural properties of mortar and concrete. The cost effectiveness of use of nano-silica in cement-based materials is also discussed. The optimum replacement percentage of cement with this nanomaterial to improve the performance of mortar and concrete is also investigated. The investigation showed that nano-silica has the ability to enhance the mechanical properties, durability and microstructural properties of concrete and mortar to a remarkable level. It also showed that the optimum content of nano-silica in concrete and mortar is 1.0-4.0% by weight of binder materials.
Effect of Column Cross Section and Concrete Compressive Strength on the Resistance of Rc Columns Subjected To Axial Loads and Loads Created by Creep
(2022) Nakipoğlu, Abdulhamit; Al-Hagri, Mohammed Gamal; Döndüren, Mahmud Sami
Reinforced concrete buildings that are not properly designed, constructed, or supervised, might not have the resistance to bear even their own weight. When the effects of deformation in the concrete over time are added to the loads, great damages and even collapses can be seen. In this study, the performance of reinforced concrete buildings under axial loads was investigated. The effect of creep in concrete over time was also evaluated. Creep deformation has been integrated into the analysis with a simple method. A total number of 20 8-storey reinforced concrete frame buildings were modeled via ETABS. In each model, only column dimensions and concrete compressive strengths have been changed. The models were analyzed under the combined effect of axial loads and creep. As a result, the effect of concrete compressive strength and column dimensions on collapse in reinforced concrete buildings under the mentioned effects was examined. The results showed that column dimensions should be much high to prevent collapse when low strength concrete is used in buildings. In addition, a formula that can be used to determine the parameters of concrete quality and column cross-sectional areas required against collapse is proposed for the preliminary design of similar types of buildings.
Citation - WoS: 2
Citation - Scopus: 3
Low-Velocity Impact Behavior of Two-Way Sfrc Slabs Strengthened With Steel Plate
(Springernature, 2024) Al-Hagri, Mohammed Gamal; Döndüren, M. Sami; Yılmaz, Tolga; Anıl, Özgür; Erol, Hakan; Şengel, Hasan Selim
Structural systems and structural elements can often suffer severe damage or even completely collapse under the effect of sudden dynamic impact loading, which is a different type of loading that is not considered during their design. Research on how structures behave under impact loading and how they can be strengthened to perform better against this type of loading has increased to avoid such undesirable severe damage. Within the scope of this study, it is aimed to improve the behavior and increase the performance of two-way steel fiber-reinforced concrete (SFRC) slabs, one of the leading structural elements that can be affected by impact loading, using steel fiber concrete (SFC) and placing steel plates on the surface of the RC slab. Within the scope of the study, the effects of placing FRC as layers in different positions within the slab and placing the steel plate on different surfaces of the slabs were examined. Impact loading was applied using a drop weight test setup designed by the authors, and the acceleration-time, displacement-time, and impact loading-time behaviors of the RC slabs were measured and interpreted. The use of fiber concrete in RC slabs and strengthened with steel plates increased the maximum acceleration values by an average of 3% and 113%, respectively. The use of fiber concrete in RC slabs reduced the maximum displacement and residual displacement values by an average of 2% and 25%, respectively. Placing steel plates on the slabs reduced the maximum displacement and residual displacement values by an average of 270% and 199%, respectively. In addition, the energy absorption capacities of RC slabs were calculated, and how they were affected by experimental variables was examined. Numerical analyses of the RC slabs tested in the study were also conducted using ABAQUS finite element software, and the results obtained were compared with the experimental ones.